Field
The present disclosure relates to a flexible thin film transistor substrate and a flexible organic light emitting display device, and more particularly, to a flexible thin film transistor substrate and a flexible organic light emitting display device in which performance does not deteriorate in spite of repeated folding.
Description of the Related Art
In a display device used in a monitor of a computer, a television (TV), or a mobile phone, an organic light emitting display device self-emitting light, a plasma display panel (PDP) and the like, and a liquid crystal display (LCD) requiring a separate light source, and the like are included.
Further, recently, a flexible display device manufactured by forming pixels, lines, and the like on a flexible substrate such as plastic which is a flexible material to display an image even though being bent like a paper has received attention as a next-generation display device.
Particularly, an organic light emitting element has received attention as a pixel of the flexible display device due to a small thickness and excellent flexibility. A flexible organic light emitting display device includes an organic light emitting element and a thin film transistor turning on or off the organic light emitting element. Furthermore, the flexible organic light emitting display device includes an inorganic insulation layer insulating electrodes of the thin film transistor from each other and an organic insulation layer disposed on the inorganic insulation layer. However, when the flexible organic light emitting display device is repetitively bent or folded, tension is applied to the inorganic insulation layer and the organic insulation layer included in the flexible organic light emitting display device. As a result, a crack may be generated in the inorganic insulation layer or the organic insulation layer. The crack may propagate to the organic light emission layer of the organic light emitting element or the active layer of the thin film transistor through the inorganic insulation layer and the organic insulation layer. As a result, performance of the organic light emission layer or the active layer may deteriorate. For example, tension generated by bending breaks bond between the inorganic insulation layer and the active layer. Thus, a phenomenon that the active layer slips over the inorganic insulation layer due to breaking the bond there between may occur. Herein this phenomenon is defined to slip phenomenon. The crack and the slip phenomenon between the active layer of the thin film transistor and the inorganic insulation layer shift a threshold voltage of the thin film transistor, and the lifespan of the flexible organic light emitting display device may be shortened.